A photodiode array absorbance detector for a liquid chromatograph has such an apparatus configuration, for example, as is illustrated in FIG. 1, and analyzes a sample that is eluted from a column of the liquid chromatograph and flows into a flow cell.
Light emitted from a light source (L) 13 placed in a light source chamber 12 provided separately from a spectroscopic chamber 11 is focused and applied onto a sample in a flow cell (FC) 15 by an entrance-side concave mirror (M1) 14. At the application point, the light is absorbed at a particular wavelength or wavelengths according to a component or components of the sample, and the resultant light is focused on a slit (S) 17 by an exit-side concave mirror (M2) 16. The light passing through the slit 17 is spectrally separated by a diffraction grating (G) 18, and the intensity is measured for each wavelength by a photodiode array (PDA) 19. In this way, an absorbance spectrum of the analytical sample in the flow cell 15 can be obtained (see, for example, Patent Document 1).